Golf ball manufacturers have been experimenting with various materials and manufacturing methods for golf balls over the years in an attempt to improve overall performance and durability and to further refine the manufacturing process.
For example, over the past years, golf ball manufacturers have been using ionomer resins for golf ball cover materials because of the durability, rebound, and scuff resistance characteristics of the materials. However, while ionomer resins are more durable than other types of golf ball layer materials, the same properties that result in durability also provide a hard “feel” and generally result in a lower spin rate and, thus, lower control, due to the hardness of the material.
Alternatively, polyurethane compositions produce “soft” covers and typically allow for greater control because of the increased spin. Because conventional polyurethane cover materials are typically formed of aromatic components, the ultraviolet degradation of the material, which leads to yellowing, led to the recent trend toward light stable cover materials, such as aliphatic polyurethane and polyurea materials. Whether aromatic or aliphatic in nature, however, the relative softness of the polyurethane and polyurea materials introduces durability issues.
Further attempts to compensate for the “hard” feel of ionomer-covered golf balls and durability and adhesion issues with polyurethane-covered and polyurea-covered golf balls have resulted in blends of hard ionomer resins, i.e., resins with hardness values of about 60 Shore D and above, with relatively softer polymeric materials. For example, blends of hard ionomers with polyurethanes have been used to form intermediate layers and cover layers of golf balls. However, such blends generally have processing difficulties associated with their use in the production of golf balls due to the incompatibility of the components. In addition, golf balls produced from these incompatible mixtures will have inferior golf ball properties such as poor durability, cut resistance, and the like.
As such, a need exists in the golf ball art for materials that have the performance benefits of polyurethane and polyurea, but higher hardness and higher flexural modulus values, as well as improved hydrophobicity. In addition, golf balls having layers formed, at least in part, from such compositions would be advantageous. The present invention addresses such materials, methods of forming the materials, and portions of golf balls formed from these materials.